ᐅ Setting WPC Fence Posts in Concrete

Hello everyone,

I hope I can get some help from you here.

After living in our new build for 3 years, we finally want to install a privacy fence. We plan to install 1.80m x 1.80m (6 ft x 6 ft) WPC fence panels along a length of 23 meters (75 ft). At the edge of our property, we have set up Bellamur 50 x 25 x 20cm (20 x 10 x 8 inches) masonry blocks. These blocks are stacked in two rows on top of each other, placed on gravel, and filled with concrete. We did this because there is a slight height difference between the street and our property. At the points where the posts will be concreted in, no concrete has been poured yet. At these spots, we can still drill through the masonry blocks into the ground, and I could also drive steel rebar into the soil.

My question is whether this will be sufficient, as the 1.80m (6 ft) fences already have a large surface area and should therefore be stable.

Thanks in advance for your answers.

The construction method is not entirely clear to me yet, but if you only plan to insert steel rods into the ground, it likely won’t be stable. The fence and wall probably won’t withstand wind pressure well, depending on wind direction and strength. Essentially, they would just rest on the gravel and be “anchored” only by the steel rods driven into the ground. To make it work, you would need to install proper foundations in that area. Also, you should check whether you are allowed to build the fence up to 1.80 m (5 ft 11 in) high. If your property is on higher ground, the total height could reach 2.30 m (7 ft 7 in) or more.

I took a few pictures since it will probably be easier to understand that way.
The idea is to drill a bit deeper into the holes.

The height should not be an issue as the bricks are almost level with the street.

Yes, you now need to drill 80cm (31.5 inches) deep and fill it with concrete. It’s best to also add steel reinforcement.

Ah, ok!

First, I would clarify the height, as there are often regulations, especially for areas facing public spaces, that do not allow more than 2 / 1.80 m (6.6 / 5.9 ft). But honestly, if you are basically just setting the posts in concrete within the wall, which is only standing on gravel, right? Then the whole thing, even if you drive some rebar into the ground, will be borderline if the wind hits the fence from the street side with higher force. I think you would definitely need proper foundations to ensure it really holds, but I can’t quite imagine how to make those now. Unless you can deepen those "hollow spots" accordingly and create foundation "piles" there.

cschiko schrieb:

Unless you can deepen those "voids" accordingly and create proper foundation "piles."

That’s hardly possible, as the stones are not particularly large and you certainly can’t get proper tools in there. The original poster should have asked this question before stacking and filling the stones, because in my opinion they need to be removed, a foundation installed underneath (a semi-rigid base of gravel plus concrete should be sufficient), and then everything rebuilt. Fill the stones at the posts with reinforcing bars and concrete; otherwise, gravel alone is enough. If you just cobble something together now, I expect the whole structure to end up in the garden or on the street at the first storm. It’s not only the pressure on the fence; there’s also a significant lever effect on the posts, which are only supported by the stacked stones, and the gravel underneath is probably not properly compacted either (since heavy machinery can’t get in).